Here is a player piano, playing The Sound of Music. It gives you a close look at the keys doing their thing and how the paper roll moves, how the words are printed off to one side. A different kind of Karaoke...

Records were originally made to play at 78 rpm (revolutions per minute) and were made of a brittle, breakable, material called 'shellac.'

1940s Reel-to-reel tape recording

1947 Dictabelts

These were vinyl belts used in offices: Someone could dictate a letter and the sound would 'record' onto the belt. A typist would take the belt and put it into a machine to hear and type up what was said.

1948 LP (Long Playing) record on vinyl

These were played on a record player: the records had a hole in the center. You would place the record on the spindle of the turntable, turn the player on, and set the arm on the record. The arm had a needle in it which sent the sound to the speakers. The record player usually had three speeds: 33-1/3, 45, and 78 for very old records.

An album (record) would have songs on both sides, and played at 33 1/3 rpm. They cost about $5.00. However, keep in mind a teen's allowance might be $5 a month. While thinner than shellac and not easy to break, vinyl records warp easily from heat: if you kept them in the sun or close to a heat source, they will curve out of shape, which ruins the sound.

1949 45 rpm record

These were singles, one song on either side. They cost about $1.00. They played at 45 rpm. You had to put an adapter in the center hole because it was too large to go on the spindle without it.

Adapter for 45s

This is what a record looks like when it's being played: The needle on the arm of the player is 'traveling' along the grooves of the record towards the hole in the middle. Hence, probably, the term "groovy."

In the 80s, DJs would usually have two players going at once and then move the turntable by hand to achieve the 'scratchy' sound popular at that time:

All recordings made by etching are actually one continuous spiral, whether on a cylinder or a vinyl record.

1958 Tape cartridge

1963 Tape cassette

1964 8 track tape

1967 Mini Cassette

1982 CD (Compact Disc)

2004 USB Flash Drive

Here is what a sound wave looks like when a computer analyzes it:

People buy about an equal amount of their music by download (such as ITunes) as they do actual CDs, about 11 million of each per year. We are also just listening to music online more and buying less of either type of music.

To learn how noise affects your hearing, see Triogenius April 6, 2015 (to your right in the Archives)